New Zealand Transport Agency has planned to close Wellington tunnels for five weeks to remedy serious safety problems. The work will start late in December when many people are on holiday and schools are closed.

More than 80,000 vehicles travel through Wellington's Mount Victoria and Terrace tunnels each day, and the tunnels have outdated ventilation fans making them serious fire hazards. Moreover, the systems are coming to the end of their natural life. Tunnel linings, lighting, drainage and emergency systems are also lagging well behind modern international standards.

Safety is precisely the reason the tunnels need $80 million facelift, without an urgent upgrade to their ventilation fans the tunnels are a serious fire risk. Work is also needed to strengthen some fittings to meet modern earthquake standards.

Closure of the tunnel will lead to chaos among the drivers. Alternative access to the eastern suburbs may lead to traffic congestion in Oriental Bay and Newtown. And the residents, whose neighbourhoods will be affected by the increased traffic, are arguing that their safety and sanity is at risk.

But the Government is planning to increase the bus services through the Hataitai bus tunnel - and extra ferry services between Seatoun, Miramar and the city - could be introduced to urge motorists to ditch their vehicles.

The project is to be completed through either a series of late night closures, which could take months, or a complete closure for up to five weeks in December.

The decision on when the work will take place is expected to be finalised by October.

Work is also needed to strengthen some fittings to meet modern earthquake standards.